The objective of the Phase I project is to prove the feasibility of the Automated Naloxone Delivery System (ANDS) by: (1) designing the physiological monitoring and prediction algorithm used to trigger the injection; (2) designing and developing prototypes of the automated naloxone injection system; (3) conducting structured interviews with potential users (opiate injectors and physicians) to determine the best automated naloxone dosing system design; and (4) designing the system to be fabricated and testing during the potential Phase II.